diff --git a/src/binding.cpp b/src/binding.cpp
index 4308466..3d573a8 100644
--- a/src/binding.cpp
+++ b/src/binding.cpp
@@ -24,14 +24,14 @@ Nan::Persistent<FunctionTemplate> RocksDBCache::constructor;
 rocksdb::Status OpenDB(const rocksdb::Options& options, const std::string& name, std::unique_ptr<rocksdb::DB>& dbptr) {
     rocksdb::DB* db;
     rocksdb::Status status = rocksdb::DB::Open(options, name, &db);
-    dbptr = std::move(std::unique_ptr<rocksdb::DB>(db));
+    dbptr = std::unique_ptr<rocksdb::DB>(db);
     return status;
 }
 
 rocksdb::Status OpenForReadOnlyDB(const rocksdb::Options& options, const std::string& name, std::unique_ptr<rocksdb::DB>& dbptr) {
     rocksdb::DB* db;
     rocksdb::Status status = rocksdb::DB::OpenForReadOnly(options, name, &db);
-    dbptr = std::move(std::unique_ptr<rocksdb::DB>(db));
+    dbptr = std::unique_ptr<rocksdb::DB>(db);
     return status;
 }
 
@@ -1093,7 +1093,9 @@ struct Context {
     uint32_t mask;
     double relev;
 
-    Context(Context const& c) = default;
+    Context() = delete;
+    Context(Context const& c) = delete;
+    Context& operator=(Context const& c) = delete;
     Context(Cover && cov,
             uint32_t mask,
             double relev)
@@ -1293,12 +1295,12 @@ double scoredist(unsigned zoom, double distance, double score) {
 
 void coalesceFinalize(CoalesceBaton* baton, std::vector<Context> && contexts) {
     if (!contexts.empty()) {
+        std::size_t max_contexts = std::min(contexts.size(),static_cast<std::size_t>(40));
         // Coalesce stack, generate relevs.
         double relevMax = contexts[0].relev;
         std::size_t total = 0;
         std::map<uint64_t,bool> sets;
         std::map<uint64_t,bool>::iterator sit;
-        std::size_t max_contexts = 40;
         baton->features.reserve(max_contexts);
         for (auto && context : contexts) {
             // Maximum allowance of coalesced features: 40.
@@ -1412,12 +1414,13 @@ void coalesceSingle(uv_work_t* req) {
         }
 
         // sort grids by distance to proximity point
+        // TODO: partial_sort here would be ideal
         std::sort(covers.begin(), covers.end(), coverSortByRelev);
+        std::size_t max_contexts = std::min(covers.size(),static_cast<std::size_t>(40));
 
         uint32_t lastid = 0;
         std::size_t added = 0;
         std::vector<Context> contexts;
-        std::size_t max_contexts = 40;
         contexts.reserve(max_contexts);
         for (auto && cover : covers) {
             // Stop at 40 contexts
@@ -1623,7 +1626,7 @@ void coalesceMulti(uv_work_t* req) {
                 contexts.emplace_back(std::move(context));
             }
         }
-
+        // TODO: partial_sort here would be ideal
         std::sort(contexts.begin(), contexts.end(), contextSortByRelev);
         coalesceFinalize(baton, std::move(contexts));
     } catch (std::exception const& ex) {